Proper Drainage for Landscaping

Positive Drainage

• The term "positive drainage" refers to water flowing away from a structure, such as a house. The finished grade shouldn't be less than 6 inches below the siding. Two percent slope -- 2 foot rise to every 100 foot run -- is the minimum for drainage from unpaved surfaces. Two percent looks flat but provides enough slope for water to drain.

Stability

• It's important that the ground be stable, especially around structures. Compact gravel material close to the foundation to prevent the ground from settling. If the grade is too flat to drain adjacent to the house, you may need to install sub-surface drainage pipes.

Swales

• Your landscape project shouldn't impact on the drainage of adjacent properties. Surface drainage is typically handled with swales, which are gentle depressions that channel runoff to an acceptable outlet. Swales will keep runoff on your property to the discharge point.